The present invention relates to a method and apparatus for forming catheter products and particularly to a method and apparatus for beveling the tip of intravenous catheters.
Intravenous catheters come substantially in two types of products. The first type is a through-the-needle catheter product wherein the catheter that is to be disposed within the vein is inserted through a sharpened cannula. The cannula is used to pierce the skin and insert the catheter and later is removed. However, this type of catheter has not met with much commercial success do to inherent flaws in the through-the-needle type delivery system. For example, the needle must be larger in diameter than the catheter being inserted. Therefore, the needle creates a larger opening on insertion than the catheter requires and creates a greater chance of leakage. Furthermore, it is difficult to remove and dispose of the needle or cannula once the catheter has been inserted.
The second and more common type of intravenous catheters is the over-the-needle catheter. In this type of product a needle or cannula has disposed thereover a catheter. The catheter is disposed such that the sharpened tip of the needle is extending from the catheter product and is used to pierce the patient's skin and insert the catheter. Once the skin and vein have been pierced, the catheter is threaded off of the needle and the needle is removed from the catheter product.
In order to ease the insertion of the over-the-needle type catheter products, it has long been known to bevel the tip of the catheter to provide a smooth transition between the surface or outer diameter of the needle or cannula and the surface or outer diameter of the catheter itself during the insertion process. There have been many methods developed for beveling the tips of catheters. For example, U.S. Pat. No. 4,661,300 to Daugherty entitled "Method and Apparatus for Flashless Tipping of an I.V. Catheter" discloses a process which was used in the early 1980's to mold a beveled tip on a catheter while simultaneously trimming the flash in order to provide a clean edge to the tip. This process, however, requires a high cost in retooling because of the wear interface between the two tool members and the cleaning necessary to unclog the mold from the trimmed flash.
Catheters have also been provided with what is actually a duel bevel. The bevel begins gently at approximately 3.degree. and then is sharper right at the tip, for example 27.degree.. The sharper bevel is provided to ease the transition to the initial OD of the catheter, while the softer bevel eases the opening to the final OD of the catheter.